A router, for example, typically has a base that contacts a work piece. A rotating tool bit is positioned relative to the base and cuts into the work piece. So as to increase the possible range of cuts that may be accommodated with a given tool bit as well as to permit the use of tool bits of different shapes and sizes, a router is conventionally provided with a depth adjustment mechanism. Fine depth adjustment is desirable for precision work, while coarse adjustment is desirable for changing bits or for doing deep cutting work.
U.S. Pat. No. 7,275,900 discloses a router which incorporates an elevating mechanism comprising a worm drive that in one position cooperates with a rack assembly mounted to the motor housing to enable fine adjustment of the position of the motor housing relative to its support base. Rotation of an eccentric lever urges the worm drive out of contact with the rack assembly in order to enable coarse adjustment of the motor housing.